Class almost taught itself. It even ended with a cliffhanger. But I wasn't so sure what would happen afterward.

The students had been reading some classical writings about human nature, and I had made a remark about our "design features." Someone asked for an example. "Don't you know how you're made?" I answered. "You give me an example."

The engineering major said, "How about bipedalism? We're made to walk on two legs."

"That's a bodily design feature," I said. "We have mental design features too."

The little guy with the beard frowned and said, "I don't follow you."

"Well, what would you say that our intellects are designed for?"

"Pursuing the truth and deliberating about what would be good to do," announced the girl with the cats-eye glasses.

"I'm glad you remember your Aristotle reading," I smiled. "What else?"

A guy in the back called out, "How about recognizing beauty?"

"That's good too," I answered. "Plato would say you've now covered all three of the most important bases: The mind is directed toward the True, the Good, and the Beautiful. Now let me throw you a curve. You've all been telling me how individuals are designed; instead tell me how the species is designed."

They looked at each other blankly. The bearded guy said hesitantly, "Well — there are two kinds of us."

"What do you mean, two kinds?"

"Two sexes."

A girl in the front said, "The first thing I notice when I meet another person is whether he's male or female." Everyone laughed.

I said, "Okay, but we need to know more about that. How are the sexes different?"

"That takes us back to anatomy," said the engineer.

"Differences between the sexes start with anatomy," I answered, "but do they end there?"

"That's not the half of it," said the girl in front. "There's something missing in men."

"Hey!" said Nathan. Laughter again. I knew Nathan from a previous course.

"I wasn't finished," said the girl. "I think something is missing in women too."

"The same things, or different things?" I asked.

"Different. Each sex is incomplete without the other."

"Curiouser and curiouser," I commented. "But remember, I was asking about our design. What would you say this 'incompleteness' suggests about it?"

The bearded guy said, "That the two sexes are designed to, well, complete each other?"

I smiled. "That's fast work, people — almost too fast. I ought to slow you down, but we're almost out of time. In natural law theory, the idea you've been working up to is called the 'complementary personal union of opposites.' You probably know its everyday name."

"Are you talking about marriage?" The girl with the cats-eye glasses was incredulous.

"Of course."

The engineering major asked, "What was that other thing you called it?"

"Complementary personal union of opposites. Complementary, because each sex balances the other; personal, because it involves the gift of self; a union, because they join to make one flesh; and of opposites, because polarity is what makes it work."

Fifteen seconds were left. The students were intrigued, but they could see the clock as well as I could, and already they were reaching for their backpacks. I was just touching my tongue to the ridge behind my teeth to make the first sound in "Dismissed," when all of a sudden Nathan exclaimed, "Hey, wait a minute!"

I cancelled the action of my tongue. The backpackers froze in mid-pickup. "Pardon?"

"I object!" he said. "Why do we have to view certain traits as masculine or feminine? Aren't we all just people?" Just at that moment the bell rang.

I laughed. "Will the Mountie arrive in time to free Little Nell from the railroad tracks? Tune in next week for the next exciting episode of Adventures in Natural Law."

Everyone headed for the door. So did Nathan, but he had a sort of thwarted look, like the look on my cat when the bird flies away just as he makes up his mind to go for it. It didn't surprise me that he turned up during office hours — Nathan, not the cat — though I wondered why he'd waited until they were all but over.

"Why didn't you answer my question?" he asked.

"You have to ask? Class was over. We can take it up next time."

"Why not now?"

I smiled, rested my chin in my hand, and pointed a thumb at the clock. "Same problem."

"You could give me a short answer," he protested.

"I'm not so sure that a short one would help. Is the question so very urgent?"

"Maybe not urgent. But it bugs me."

"Why?"

"Because it keeps coming up. Like the other day, when I was reading an article in a magazine about 'recovering a sense of manliness.'"

"What did the author think manliness requires?"

"Being honorable, courageous, self-restrained, zealous on behalf of a good cause — things like that."

"Things like that bug you?"

"It bugs me that they're considered 'manly.' They seem pretty gender-neutral to me."

"Aren't there any qualities you'd regard as distinctively manly or womanly?"

He grinned. "I'm asking the questions here, Prof."

I smiled. "Are you, now?"

"That's right. C'mon. I just want your own opinion. Five minutes."

"What if I can't answer in five minutes?"

"Then I'll come back another time."

"What's the question again?"

"Can't a woman be honorable, courageous, self restrained and all that?"

"In one sentence: Of course she can."

"Then they're the same."

"I didn't say that. There's no such thing as a generic person. There are only men and women."

"But you just said —"

"That's the problem with short answers," I said.

"Well, you still owe me four minutes and 30 seconds."

"Men and women can both be courageous," I said, "but a man's courage and a woman's courage are normally different."

"You mean she's less courageous?"

"I didn't say less. I said different."

"Courage is courage. Self-restraint is self-restraint."

"Are all instances of courage and self-restraint the same?"

"Instances of — how's that again?"

"Forget about men and women for a minute," I suggested. "Think of it like this. An apartment house has caught on fire. The fire crew is trying to control the blaze and get the people out. Police are warning the crowd to keep back. With me so far?"

"Yeah."

"Let's say you're a fireman. What do the virtues of courage and self-restraint require of you?"

"Courage would mean going in there and doing my job. Like you said, trying to save the people and control the fire."

"And self-restraint?"

"That's harder. Um — I guess it would mean not losing my head, remembering my training, stuff like that."

"Now let's say you're not a fireman but one of the people on the street. Several of your friends are trapped in the building and you're afraid of what will happen if they don't get out in time. Would it be an act of courage to dash inside the building to rescue them?"

"No. I'm not a fireman. If I ran in there I'd just make their job 20 times harder."

"So courage requires different things from a fireman than from you?"

"I guess so, yeah. Running in wouldn't show I've got courage. It would only show I don't have self-restraint."

"Does that mean that since you're not a fireman you don't need courage?"

"No-o-o, I think I do."

"What do you need it for?" I asked.

"We said in class once that courage is about how you deal with fear."

"So?"

"Well, I'm afraid for my friends in the building, right?"

"So what does courage require of you?"

"I guess — not panicking, not encouraging other people in the crowd to panic, stuff like that. Keeping my head in case there's something I can do, like if a fireman needs me to tell him how many people are still in the house. And in case there's a God, I guess staying calm enough to focus and pray."

"All right. And you've already told me what self-restraint requires of you."

"Yeah. Staying put."

"Do you see what I'm driving at with by talking about firemen and people on the street?"

"I think so. Both need courage, and both need self-restraint, but they need them in different ways. I guess they might even need them equally. I mean, if I was a mother and I was afraid because my child was in the building, courage would really be hard."

"I think so too."

"But that's not how I would have thought about it if you hadn't asked those questions."

"Why not?"

"Well, I get it that the bystander needs courage too, but courage is a more obvious virtue for the fireman. Know what I mean? And I get it that the fireman needs self-restraint too, but self-restraint is a more obvious virtue for the bystander. So you'd think that only the fireman needs courage and only the bystander needs self-restraint, but that's not how it is."

"That's how I see it too. Now back to what we were talking about at first."

"You mean men and women?"

"Right. Do you see how it might be that men and women also need all the same virtues, but need them in different ways?"

He stared at me for a few seconds. Then he said slowly, "I see what you're saying. Men do stuff, like the firemen, right? And women are just spectators, like the crowd."

I stared back in dismay. "Oh-h-h, Nathan, you're getting me all wrong."

READ PART 2